Among flat panel display devices, Thin-film Transistor Liquid Crystal Display (TFT-LCD) has a dominant role due to its advantages of small size, low power consumption, low fabrication cost, low radiation and the like.
Oxide Thin-film Transistor (OTFT) has the advantages of ultra thin thickness, light weight, low power consumption and the like, and thus the OTFT not only can be applied to the liquid crystal display panel, but also provides a possibility of applying organic light emitting display panel as a new generation of display panel in the future.
The conventional fabrication process of an array substrate is as follows: forming a gate electrode on a base substrate, depositing a gate insulating layer, depositing an active layer, forming source and drain electrodes, depositing a passivation layer and forming a pixel electrode.
However, the conventional fabrication process as described above has the following drawbacks. Copper (Cu) or Cu alloy is used to form the gate electrode and the source and drain electrodes, and in this case, Cu may diffuse into the active layer due to its relatively active property. Therefore, Cu is apt to contaminate the active layer, so that the carrier mobility may be reduced and defects may occur in the resultant product.